SDH (Synchronous Digital Hierarchy, synchronous digital hierarchy) is an integrated information transport network operated by a uniform network management system, integrating functions such as multiplexing, line transmission and switching. Due to too high maintenance costs, an SDH network is no longer expanded in the prior art, and a new PTN (Packet Transport Network, packet transport network) is built in place of the existing SDH network. However, numerous TDM (Time Division Multiplex, time division multiplex) circuits and services existing in the SDH network still need to be borne by the PTN network. Therefore, in a case that a PTN network replaces an SDH network, a technology of pseudo wire is used on the SDH network side to emulate an SDH/Sonet (Synchronous Optical Network, synchronous optical network) service, and transmit the emulated data to a peer SDH network transparently through the PTN network, thereby implementing service bearing in the case that a PTN network replaces an SDH network.
In the existing emulation technology, only SDH transmitter-side virtual containers or Sonet payloads are emulated and transmitted transparently, but it is not practicable to emulate and transparently transmit an AU (Administrative Unit, administrative unit) pointer. Instead, a position of a J1 byte in frame data is recorded and placed in a CEP (Circuit Emulation over Packet, circuit emulation over packet) packet header, and a pointer is re-generated at downlink on the SDH peer side according to the position of the J1 byte. In practical application, some telecom operators need to transparently transmit the AU pointer, that is, emulate and transparently transmit the content of the entire AU. The prior art provides no solution to emulating and transparently transmitting the AU pointer.